1. Field of the Invention
The present invention relates to a solid-state image sensor and a camera incorporating the solid state image sensor.
2. Description of the Related Art
When high-energy particles enter a solid-state image sensor, a single-event latch-up (SEL) can occur. The cosmic rays in outer space and radiation in a nuclear power plant or radiation image diagnosis can be raised as examples of high-energy particles. An SEL can occur, for example, in a thyristor structure in which pn junctions are connected in series in a CMOS structure. If an SEL occurs, the power source line and the ground line become conductive, and the operation of an apparatus that lacks a safeguard is disabled by the occurrence of the SEL. Therefore, when an SEL occurs, it becomes necessary to temporarily shut off the power supply to an apparatus and later restart the power supply.
Japanese Patent Laid-Open No. 2006-350425 relates to a semiconductor device that is used in a radioactive environment. The semiconductor device includes a detection unit that detects the occurrence of an SEL and a compensating circuit that turns on/off the power supply in accordance with the detection result. International Publication No. 2002/042797 relates to a radiation image diagnosis apparatus. The radiation image diagnosis apparatus has a function that monitors the supply of power to each of a plurality of element blocks, stops the supply of power to an ASIC which processes the signals from the plurality of blocks when an abnormality is detected, and corrects the data based on the duration of the time in which the supply of power was stopped.
In an arrangement which temporarily shuts off, when a latch-up occurs in a solid-state image sensor, power supply to the solid-state image sensor and later restarts the power supply, an image cannot be obtained during a power supply shutoff period. In the case of moving image sensing, an image may become unobtainable over a period of several frames.